The present invention relates to the field of molecular biology. The present invention discloses compositions comprising the nucleotide sequence of Haemophilus influenzae, fragments thereof and usage in industrial fermentation and pharmaceutical development.
The complete genome sequence from a free living cellular organism has never been determined. The first mycobacterium sequence should be completed by 1996, while E. coli and S. cerevisae are expected to be completed before 1998. These are being done by random and/or directed sequencing of overlapping cosmid clones. No one has attempted to determine sequences of the order of a megabase or more by a random shotgun approach.
H. influenzae is a small (approximately 0.4xc3x971 micron) non-motile, non-spore forming, germ-negative bacterium whose only natural host is human. It is a resident of the upper respiratory mucosa of children and adults and causes otitis media and respiratory tract infections mostly in children. The most serious complication is meningitis, which produces neurological sequelae in up to 50% of affected children. Six H. influenzae serotypes (a through f) have been identified based on immunologically distinct capsular polysaccharide antigens. A number of non-typeable strains are also known. Serotype b accounts for the majority of human disease.
Interest in the medically important aspects of H. influenzae biology has focused particularly on those genes which determine virulence characteristics of the organism. A number of the genes responsible for the capsular polysaccharide have been mapped and sequenced (Kroll et al., Mol. Microbiol. 5(6):1549-1560 (1991)). Several outer membrane protein (OMP) genes have been identified and sequenced (Langford et al, J. Gen. Microbiol. 138:155-159 (1992)). The lipoligosaccharide (LOS) component of the outer membrane and the genes of its synthetic pathway are under intensive study (Weiser et al., J. Bacteriol. 172:3304-3309 (1990)). While a vaccine has been available since 1984, the study of outer membrane components is motivated to some extent by the need for improved vaccines. Recently, the catalase gene was characterized and sequenced as a possible virulence-related gene (Bishni et al., in press). Elucidation of the H. influenzae genome will enhance the understanding of how H. influenzae causes invasive disease and how best to combat infection.
H. influenzae possesses a highly efficient natural DNA transformation system which has been intensively studied in the non-encapsulated (R), serotype d strain (Kahn and Smith, J. Membrane Biology 81:89-103 (1984)). At least 16 transformation-specific genes have been identified and sequenced. Of these, four are regulatory (Redfield, J Bacteriol. 173:5612-5618 (1991), and Chandler, Proc. Natl. Acad. Sci. USA 89:1626-1630 (1992)), at least two are involved in recombination processes (Barouki and Smith, J. Bacteriol. 163(2):629-634 (1985)), and at least seven are targeted to the membranes and periplasmic space (Tomb et al., Gene 104:1-10 (1991), and Tomb, Proc. Natl. Acad. Sci. USA 89:10252-10256 (1992)), where they appear to function as structural components or in the assembly of the DNA transport machinery. H. influenzae Rd transformation shows a number of interesting features including sequence-specific DNA uptake, rapid uptake of several double-stranded DNA molecules per competent cell into a membrane compartment called the transformasome, linear translocation of a single strand of the donor DNA into the cytoplasm, and synapsis and recombination of the strand with the chromosome by a single-strand displacement mechanism. The H. influenzae Rd transformation system is the most thoroughly studied of the gram-negative systems and distinct in a number of ways from the gram-positive systems.
The size of H. influenzae Rd genome has been determined by pulsed-field agarose gel electrophoresis of restriction digests to be approximately 1.9 Mb, making its genome approximately 40% the size of E. coli (Lee and Smith, J. Bacteriol. 170:4402-4405 (1988)). The restriction map of H. influenzae is circular (Lee et al., J. Bacteriol. 171:3016-3024 (1989), and Redfield and Lee, xe2x80x9cHaemophilus influenzae Rdxe2x80x9d, pp. 2110-2112, In O""Brien, S. J. (ed), Genetic Maps: Locus Maps of Complex Genomes, Cold Spring Harbor Press, N.Y.). Various genes have been mapped to restriction fragments by Southern hybridization probing of restriction digest DNA bands. This map will be valuable in verification of the assembly of a complete genome sequence from randomly sequenced fragments. GenBank currently contains about 100 kb of non-redundant H. influenzae DNA sequences. About half are from serotype b and half from Rd.
The present invention is based on the sequencing of the Haemophilus influenzae Rd genome. The primary nucleotide sequence which was generated is provided in SEQ ID NO:1.
The present invention provides the generated nucleotide sequence of the Haemophilus influenzae Rd genome, or a representative fragment thereof, in a form which can be readily used, analyzed, and interpreted by a skilled artisan. In one embodiment, present invention is provided as a contiguous string of primary sequence information corresponding to the nucleotide sequence depicted in SEQ ID NO:1.
The present invention further provides nucleotide sequences which are at least 99.9% identical to the nucleotide sequence of SEQ ID NO:1.
The nucleotide sequence of SEQ ID NO:1, a representative fragment thereof, or a nucleotide sequence which is at least 99.9% identical to the nucleotide sequence of SEQ ID NO:1 may be provided in a variety of mediums to facilitate its use. In one application of this embodiment, the sequences of the present invention are recorded on computer readable media. Such media includes, but is not limited to: magnetic storage media, such as floppy discs, hard disc storage medium, and magnetic tape; optical storage media such as CD-ROM; electrical storage media such as RAM and ROM; and hybrids of these categories such as magnetic/optical storage media.
The present invention further provides systems, particularly computer-based systems which contain the sequence information herein described stored in a data storage means. Such systems are designed to identify commercially important fragments of the Haemophilus influenzae Rd genome.
Another embodiment of the present invention is directed to isolated fragments of the Haemophilus influenzae Rd genome. The fragments of the Haemophilus influenzae Rd genome of the present invention include, but are not limited to, fragments which encode peptides, hereinafter open reading frames (ORFs), fragments which modulate the expression of an operably linked ORF, hereinafter expression modulating fragments (EMFs), fragments which mediate the uptake of a linked DNA fragment into a cell, hereinafter uptake modulating fragments (UMFs), and fragments which can be used to diagnose the presence of Haemophilus influenzae Rd in a sample, hereinafter, diagnostic fragments (DFs).
Each of the ORF fragments of the Haemophilus influenzae Rd genome disclosed in Tables 1(a) and 2, and the EMF found 5 to the ORF, can be used in numerous ways as polynucleotide reagents. The sequences can be used as diagnostic probes or diagnostic amplification primers for the presence of a specific microbe in a sample, for the production of commercially important pharmaceutical agents, and to selectively control gene expression.
The present invention further includes recombinant constructs comprising one or more fragments of the Haemophilus influenzae Rd genome of the present invention. The recombinant constructs of the present invention comprise vectors, such as a plasmid or viral vector, into which a fragment of the Haemophilus influenzae Rd has been inserted.
The present invention further provides host cells containing any one of the isolated fragments of the Haemophilus influenzae Rd genome of the present invention. The host cells can be a higher eukaryotic host such as a mammalian cell, a lower eukaryotic cell such as a yeast cell, or can be a procaryotic cell such as a bacterial cell.
The present invention is further directed to isolated proteins encoded by the ORFs of the present invention. A variety of methodologies known in the art can be utilized to obtain any one of the proteins of the present invention. At the simplest level, the amino acid sequence can be synthesized using commercially available peptide synthesizers. In an alternative method, the protein is purified from bacterial cells which naturally produce the protein. Lastly, the proteins of the present invention can alternatively be purified from cells which have been altered to express the desired protein.
The invention further provides methods of obtaining homologs of the fragments of the Haemophilus influenzae Rd genome of the present invention and homologs of the proteins encoded by the ORFs of the present invention. Specifically, by using the nucleotide and amino acid sequences disclosed herein as a probe or as primers, and techniques such as PCR cloning and colony/plaque hybridization, one skilled in the art can obtain homologs.
The invention further provides antibodies which selectively bind one of the proteins of the present invention. Such antibodies include both monoclonal and polyclonal antibodies.
The invention further provides hybridomas which produce the above-described antibodies. A hybridoma is an immortalized cell line which is capable of secreting a specific monoclonal antibody.
The present invention further provides methods of identifying test samples derived from cells which express one of the ORF of the present invention, or homolog thereof. Such methods comprise incubating a test sample with one or more of the antibodies of the present invention, or one or more of the DFs of the present invention, under conditions which allow a skilled artisan to determine if the sample contains the ORF or product produced therefrom.
In another embodiment of the present invention, kits are provided which contain the necessary reagents to carry out the above-described assays.
Specifically, the invention provides a compartmentalized kit to receive, in close confinement, one or more containers which comprises: (a) a first container comprising one of the antibodies, or one of the DFs of the present invention; and (b) one or more other containers comprising one or more of the following: wash reagents, reagents capable of detecting presence of bound antibodies or hybridized DFs.
Using the isolated proteins of the present invention, the present invention further provides methods of obtaining and identifying agents capable of binding to a protein encoded by one of the ORFs of the present invention. Specifically, such agents include antibodies (described above), peptides, carbohydrates, pharmaceutical agents and the like. Such methods comprise the steps of:
(a) contacting an agent with an isolated protein encoded by one of the ORFs of the present invention; and
(b) determining whether the agent binds to said protein.
The complete genomic sequence of H. influenzae will be of great value to all laboratories working with this organism and for a variety of commercial purposes. Many fragments of the Haemophilus influenzae Rd genome will be immediately identified by similarity searches against GenBank or protein databases and will be of immediate value to Haemophilus researchers and for immediate commercial value for the production of proteins or to control gene expression. A specific example concerns PHA synthase. It has been reported that polyhydroxybutyrate is present in the membranes of H. influenzae Rd and that the amount correlates with the level of competence for transformation. The PHA synthase that synthesizes this polymer has been identified and sequenced in a number of bacteria, none of which are evolutionarily close to H. influenzae. This gene has yet to be isolated from H. influenzae by use of hybridization probes or PCR techniques. However, the genomic sequence of the present invention allows the identification of the gene by utilizing search means described below.
Developing the methodology and technology for elucidating the entire genomic sequence of bacterial and other small genomes has and will greatly enhance the ability to analyze and understand chromosomal organization. In particular, sequenced genomes will provide the models for developing tools for the analysis of chromosome structure and function, including the ability to identify genes within large segments of genomic DNA, the structure, position, and spacing of regulatory elements, the identification of genes with potential industrial applications, and the ability to do comparative genomic and molecular phylogeny.